The invention relates to a reamer, in particular to a single-cutter reamer having a base body in the circumferential wall of which, a cutting tip and at least one guide bead, received in a groove extending in the longitudinal direction of the base body, are mounted. Single-cutter reamers of the described type are used for machining bore surfaces in workpieces. For obtaining a bore with optimal surface qualities and very precise bore dimensions, a relative rotation between the workpiecee and a tool, the reamer, is effected, and the reamer is introduced into the bore of the workpiece. By rotation of the tool, chips are cut of the bore wall with the cutting edge of the cutting tip, which cutting edge has an orbit that is larger then the orbit of the outermost surface of the guide bead of the reamer. The reamer is guided inside the bore by a least one, preferably two guide beads. Because the cutting tip exerts a cutting force on the bore wall, the guide beads apply a corresponding supporting force. The resulting friction between the guide beads and the bore wall leads to build-up of the material of the machined bore wall on the guide beads, especially in the regions of the guide bead that contact the bore wall under high pressure. Because of the build-up of material on the guide beads, the once established diameter cannot be maintained. Because of this, a reliable guiding of the tool inside the bore cannot be assured any more, and fluctuations, which lead to a non-round bore with reduced surface qualities, take place.
Accordingly, the object of the invention is a reamer having an extremely long service life due to a reduced build-up of material on the guide beads.